Piston rod for power hammers



. we! 'I H. A. HARRIS) 2,377,417

June 5, 1945.

' PISTON ROD FOR POWER HAMMERS Filed July s, 1943 2 Sheets-Sheet 1 5 1?; "4 i JTQMw/M HARRIS June 5, 1945.

//AMM Ww Patented June 5, 1945 UNITED STATES PATENT OFFICE 2,377,417 a a I PISTON Ron FOR POWER HAMMERS Harry A. Harris, Chicago, Ill. 7 Application July s, 1943, Serial No. 493,357

4 Claims. (01. 287-108) My invention relates to piston rods for power hammers, particularly steam drop hammers.

Piston rods for steam drop hammers are currently cylindrical one piece masses of steelpreferably chrome-nickel-molybdenum steel for heavy work-sometimes ten or more feet in length. Breakage is a continuing source of work interruption and expense. Usually breaks occur within or a few inches above the junction between the rod and the ram or head of the hammer. They are thought generally to be caused by fatigue of the metal which results from vibration occasioned by the imperceptible whipping of the rod brought about by the rapid movements and impacts of the head, unsymmetrical distribution of metal within die cavities, non-uniformity of applied work-pressure and guide friction. Breaks not only result in production stoppage, but also in considerable extra work and expense for replacement and in loss of material.

The principal object of my invention is to provide an improved power hammer piston rod.

Another object is to provide a rod wherein the vibration tendency is reduced with the result that fatigue is retarded and longer life insured.

A further object is to provide a rod such that only the part most susceptible to breakage needs be replaced if breakage does occur.

Other objects and advantages will hereinafter appear.

In general, my invention contemplates a composite rod of four parts, two axially aligned sections between which is interposed a compression piece, the confronting faces of the rod sections and compression piece fitting together on spheroidal surfaces, and a coupling that unites the sections and compression piece into a unitary and seemingly rigid structure.

In the accompanying drawings wherein two typical embodiments of my invention are illustrated:

Fig. l is a side elevation, largely diagrammatic, of a power hammer equipped with a piston rod constructed according to my invention;

Fig. 2 is an enlarged side elevation and partial section of the preferred rod assembly;

Fig; 3 is a section on the line 3-3 of Fig. 2;

Fig. 4 is a side elevation and partial section of a. modified construction; and

Fig. 5 is a section on the line 5-5 of Fig. 4.

In general, a power press includes a frame l0 having hammer head guides II and a fixed die support [2; a movable hammer head l3 carrying a die complementary to the die supported by the frame; a, cylinder-piston assembly l4, most frequently steam operated, for actuating thev hammer head, sometimes merely by lifting it to permit it to drop by gravity on its work stroke and sometimes to actuate the head on both the retracting and work strokes; and a piston rod interconnecting the piston and the hammer head. The present. invention concerns itself only with the piston rod.

Referring now particularly to Figs. 2 and 3, the preferred rod construction includes two cylindrical axially aligned sections and 2| which are joined end to end by a coupling 22.- The upperend of rod-section 20 is connected to the "hammers piston in any appropriate manner. The lower end of rod-section 2l is connected to the hammer head H1 in any approved manner, a taper press fit is indicated because that is a widely used method. These rod-sections may be formed from metal suitable for the service expected of the hammer; chrome-nickel-molybdenum, steel is'currently very extensively used. If desired and feasible under special conditions, the lower rod-section may be made integral with the hammer head or ram. Usually the lower section should not project very far above the top of the head so that the coupling to be hereinafter described is located as near as possible to the top of the ram.

The confronting ends 'of rod-sections 20 and 2| are fashioned with cavities to provide spheroidal contact surfaces and 26, respectively. A compression piece 21 is interposed between the confronting ends of sections 20 and 2|. This compression piece is preferably made from the same material as the rod-sections, although under some conditions and for some services a different material may prove superior. Preferably it is formed in ellipsoidal shape to provide convexly spheroidal surfaces 28 and 29 which are complementary to and accurately fit the surfaces 25 and 26, respectively, of the rod-section cavities. the rod-section cavities may be somewhat smaller across than the diameter of the sections, and the spheroidal surfaces of the compression piece need not meet in a plane, but the piece may be circumferentially somewhat flattened, as shown clearly in Fig. 2.

The coupling 22, which joins the two rod-sections and compression piece into a unitary structure, is shown as a collar formed of two semicylindrical parts and 36. However, if desired, it may be formed in three or more pieces. Each of the parts of the collar is formed with inwardly In order to eliminate sharp edges,

projecting semi annular bosses or lugs 31-38 and 39-40, respectively, which fit into complementary annular channels or grooves II and 42 formed in the rod-sections 2| and 20, respective- 1y, The coupling collar sections may be clamped piece, the coupling collar and the retaining sleeve are assembled, they form a unitary composite piston rod; A tighter clamping action and other wise better fit between the coupling collar and sleeve may usually be attained by tapering slightly the contiguous surfaces thereof; Preferablythe central region of the bore through the assembled coupling collar sections is slightly larger than the diameter of the rod-sections so as to provide a small clearance 48 therebetwe'en.

The modification shown in: Figs. 4 and 5 differs from the preferred embodiment heretofore described. merely in the construction of the retaining sleeve. Here the sleeve; instead of being in. onepiece which is for. example, shrimlr. tightly into position, is formed. in two semi-cylindrical parts clamped and tightly held by bolts 50 passing through appropriate holes in radially projecting longitudinaleflanges SI and 52 formed upon the collar-'sections ii and 36, respectively. l

The division of the rod into. two axially aligned sections renders, it unnecessary to scrap an entire rod when a break occurs. Experience has-demonstrated that breaksusually appear in "the part of therodwhiclnfits within theham'mer head, or a short distance: above the head. with my new rod, when a break oocurs the broken section may be removedand. replaced by a newsection. And breakage is lessapt to occur The spheroidal surface: between the two rod-sections and. interposed compression piece result in something. comparable to a ball; and socket joint, even thoughthe coupling seems tounlte the parts into a rigid. unit; Thus, theiolnt seems to compensate for inequalities in the distribution of weight and the pressures at the hammer head, in guide friction, andfor mined perhaps other reasons which are not yet fully understood, the imperceptible but none the less fatigue production vi-- 'brations are effectively-lessened, if they are not eliminated. c

Having thlllg described my invention, what I claim Barlow and desire to secure by Letters Patent of the Unitedstates 1. A power hammer piston rod comprising two axially aligned but separated sections of cylin drical metal rod and a metallic compression piece interposed between the confronting ends of said sections, the confronting end faces of the rod sections and the compression piece being formed with complementary spheroidal interfitting surfaces, a multi-piece coupling fitting about and uniting the rod sections and compression piece, each rod section. and the coupling having complementazy projections and depressions for preventing axial relative movement therebetween,

and means for clamping the parts of the coupling together and about the rod sections and compression piece.

2. A power hammer piston rod comprising two axially disposed sections of cylindrical metal rod, the confronting end faces of the two sections beingprovided with spheroidal cavities, a metallic compression piece interposed between the two red sections and having spheroidal faces complementary to-and fitting the cavities of the two sections, a-multi-piece coupling for uniting the two rod sections and compression piece, each section sndthe coupling having complementary projections and depressions for preventing axial relative' moment therebetween, and means for clamping the parts of the coupling together and about the rod sectionsand compression piece.

3. A power hammer piston rod- Comprising two axially aligned sections of cylindrical metal rod, the confronting end faces of the two sections being provided with spheroidal cavities, a spheroida-l metallic compression piece separating the two rod sections-and fitting the confronting cavities thereof, a multi-piece coupling fitting about and unitingthe rod sections and compression piece, each section and the coupling having annular complementary projections and depressions for preventing axial relative movement therebetween, and a retaining ring shrunk upon the coupling to retain the parts thereof together.

-4. A power hammer piston rodcomprising two axially aligned-sections of cylindrical metal rod, the confronting end faces of the two sections being provided with spheroidal cavities, a metallic spheroidal compression piece separating the two rod sections and fitting the confronting cavities thereof, a muIti-piece coupling fitting about and uniting the rod sections and compression piece,

each section and the coupling having annular complementary projections and depressions for preventing axial relative movement therebetween a retaining ringformed of complementary parts fitting around the coupling sections, and

ring parts together.

means for. clamping the HARRY A. HARRIS. 

